Answer:
He volunteered 10 hrs 15 min on average.
Step-by-step explanation:
The first week: 8 hrs
The second week: 12 hrs
The third week: 12 hrs
The fourth week: 9 hrs
8 + 12 + 12 + 9 = 41 hrs total
41 hours/4 weeks = 10.25 hrs (10 hrs 15 min)
You set up a proportion so: 12/x and 40/100
Cross multiply so 12 times 100 = 1200
and 40 times x = 40x
1200 divided by 40 = 30 minutes total
You know that he already know he spent 12 minutes doing it so
30 - 12 = 18 more minutes
Fourty six thousand and fifty six. In expanded form it'll look like this:
40,000
6,000
0
50
6
